import {
	Color,
	Matrix4,
	Mesh,
	PerspectiveCamera,
	Plane,
	ShaderMaterial,
	UniformsUtils,
	Vector3,
	Vector4,
	WebGLRenderTarget,
	HalfFloatType
} from "three";

class Reflector extends Mesh {
	constructor(geometry, options = {}) {
		super(geometry);

		this.isReflector = true;

		this.type = "Reflector";
		this.camera = new PerspectiveCamera();

		const scope = this;

		const color = (options.color !== undefined) ? new Color(options.color) : new Color(0x7F7F7F);
		const textureWidth = options.textureWidth || 512;
		const textureHeight = options.textureHeight || 512;
		const clipBias = options.clipBias || 0;
		const shader = options.shader || Reflector.ReflectorShader;
		const multisample = (options.multisample !== undefined) ? options.multisample : 4;

		//

		const reflectorPlane = new Plane();
		const normal = new Vector3();
		const reflectorWorldPosition = new Vector3();
		const cameraWorldPosition = new Vector3();
		const rotationMatrix = new Matrix4();
		const lookAtPosition = new Vector3(0, 0, -1);
		const clipPlane = new Vector4();

		const view = new Vector3();
		const target = new Vector3();
		const q = new Vector4();

		const textureMatrix = new Matrix4();
		const virtualCamera = this.camera;

		const renderTarget = new WebGLRenderTarget(textureWidth, textureHeight, {samples: multisample, type: HalfFloatType});

		const material = new ShaderMaterial({
			name: (shader.name !== undefined) ? shader.name : "unspecified",
			uniforms: UniformsUtils.clone(shader.uniforms),
			fragmentShader: shader.fragmentShader,
			vertexShader: shader.vertexShader
		});

		material.uniforms[ "tDiffuse" ].value = renderTarget.texture;
		material.uniforms[ "color" ].value = color;
		material.uniforms[ "textureMatrix" ].value = textureMatrix;

		this.material = material;

		this.onBeforeRender = function (renderer, scene, camera) {
			reflectorWorldPosition.setFromMatrixPosition(scope.matrixWorld);
			cameraWorldPosition.setFromMatrixPosition(camera.matrixWorld);

			rotationMatrix.extractRotation(scope.matrixWorld);

			normal.set(0, 0, 1);
			normal.applyMatrix4(rotationMatrix);

			view.subVectors(reflectorWorldPosition, cameraWorldPosition);

			// Avoid rendering when reflector is facing away

			if (view.dot(normal) > 0) return;

			view.reflect(normal).negate();
			view.add(reflectorWorldPosition);

			rotationMatrix.extractRotation(camera.matrixWorld);

			lookAtPosition.set(0, 0, -1);
			lookAtPosition.applyMatrix4(rotationMatrix);
			lookAtPosition.add(cameraWorldPosition);

			target.subVectors(reflectorWorldPosition, lookAtPosition);
			target.reflect(normal).negate();
			target.add(reflectorWorldPosition);

			virtualCamera.position.copy(view);
			virtualCamera.up.set(0, 1, 0);
			virtualCamera.up.applyMatrix4(rotationMatrix);
			virtualCamera.up.reflect(normal);
			virtualCamera.lookAt(target);

			virtualCamera.far = camera.far; // Used in WebGLBackground

			virtualCamera.updateMatrixWorld();
			virtualCamera.projectionMatrix.copy(camera.projectionMatrix);

			// Update the texture matrix
			textureMatrix.set(
				0.5, 0.0, 0.0, 0.5,
				0.0, 0.5, 0.0, 0.5,
				0.0, 0.0, 0.5, 0.5,
				0.0, 0.0, 0.0, 1.0
			);
			textureMatrix.multiply(virtualCamera.projectionMatrix);
			textureMatrix.multiply(virtualCamera.matrixWorldInverse);
			textureMatrix.multiply(scope.matrixWorld);

			// Now update projection matrix with new clip plane, implementing code from: http://www.terathon.com/code/oblique.html
			// Paper explaining this technique: http://www.terathon.com/lengyel/Lengyel-Oblique.pdf
			reflectorPlane.setFromNormalAndCoplanarPoint(normal, reflectorWorldPosition);
			reflectorPlane.applyMatrix4(virtualCamera.matrixWorldInverse);

			clipPlane.set(reflectorPlane.normal.x, reflectorPlane.normal.y, reflectorPlane.normal.z, reflectorPlane.constant);

			const projectionMatrix = virtualCamera.projectionMatrix;

			q.x = (Math.sign(clipPlane.x) + projectionMatrix.elements[ 8 ]) / projectionMatrix.elements[ 0 ];
			q.y = (Math.sign(clipPlane.y) + projectionMatrix.elements[ 9 ]) / projectionMatrix.elements[ 5 ];
			q.z = -1.0;
			q.w = (1.0 + projectionMatrix.elements[ 10 ]) / projectionMatrix.elements[ 14 ];

			// Calculate the scaled plane vector
			clipPlane.multiplyScalar(2.0 / clipPlane.dot(q));

			// Replacing the third row of the projection matrix
			projectionMatrix.elements[ 2 ] = clipPlane.x;
			projectionMatrix.elements[ 6 ] = clipPlane.y;
			projectionMatrix.elements[ 10 ] = clipPlane.z + 1.0 - clipBias;
			projectionMatrix.elements[ 14 ] = clipPlane.w;

			// Render
			scope.visible = false;

			const currentRenderTarget = renderer.getRenderTarget();

			const currentXrEnabled = renderer.xr.enabled;
			const currentShadowAutoUpdate = renderer.shadowMap.autoUpdate;

			renderer.xr.enabled = false; // Avoid camera modification
			renderer.shadowMap.autoUpdate = false; // Avoid re-computing shadows

			renderer.setRenderTarget(renderTarget);

			renderer.state.buffers.depth.setMask(true); // make sure the depth buffer is writable so it can be properly cleared, see #18897

			if (renderer.autoClear === false) renderer.clear();
			renderer.render(scene, virtualCamera);

			renderer.xr.enabled = currentXrEnabled;
			renderer.shadowMap.autoUpdate = currentShadowAutoUpdate;

			renderer.setRenderTarget(currentRenderTarget);

			// Restore viewport

			const viewport = camera.viewport;

			if (viewport !== undefined) {
				renderer.state.viewport(viewport);
			}

			scope.visible = true;
		};

		this.getRenderTarget = function () {
			return renderTarget;
		};

		this.dispose = function () {
			renderTarget.dispose();
			scope.material.dispose();
		};
	}
}

Reflector.ReflectorShader = {

	name: "ReflectorShader",

	uniforms: {

		"color": {
			value: null
		},

		"tDiffuse": {
			value: null
		},

		"textureMatrix": {
			value: null
		}

	},

	vertexShader: /* glsl */`
		uniform mat4 textureMatrix;
		varying vec4 vUv;

		#include <common>
		#include <logdepthbuf_pars_vertex>

		void main() {

			vUv = textureMatrix * vec4( position, 1.0 );

			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

			#include <logdepthbuf_vertex>

		}`,

	fragmentShader: /* glsl */`
		uniform vec3 color;
		uniform sampler2D tDiffuse;
		varying vec4 vUv;

		#include <logdepthbuf_pars_fragment>

		float blendOverlay( float base, float blend ) {

			return( base < 0.5 ? ( 2.0 * base * blend ) : ( 1.0 - 2.0 * ( 1.0 - base ) * ( 1.0 - blend ) ) );

		}

		vec3 blendOverlay( vec3 base, vec3 blend ) {

			return vec3( blendOverlay( base.r, blend.r ), blendOverlay( base.g, blend.g ), blendOverlay( base.b, blend.b ) );

		}

		void main() {

			#include <logdepthbuf_fragment>

			vec4 base = texture2DProj( tDiffuse, vUv );
			gl_FragColor = vec4( blendOverlay( base.rgb, color ), 0.1 );

			#include <tonemapping_fragment>
			#include <colorspace_fragment>

		}`
};

export {Reflector};
